Induction of allergic inflammation by interleukin-18 in experimental animal models

Authors

  • Hiroko Tsutsui,

    1. Department of Immunology & Medical Zoology, Hyogo College of Medicine, Nishinomiya, Japan.
    2. CREST. Japan Science and Technology Agency, Kawaguchi, Japan.
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  • Tomohiro Yoshimoto,

    1. Department of Immunology & Medical Zoology, Hyogo College of Medicine, Nishinomiya, Japan.
    2. CREST. Japan Science and Technology Agency, Kawaguchi, Japan.
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  • Nobuki Hayashi,

    1. Department of Immunology & Medical Zoology, Hyogo College of Medicine, Nishinomiya, Japan.
    2. CREST. Japan Science and Technology Agency, Kawaguchi, Japan.
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  • Hitoshi Mizutani,

    1. CREST. Japan Science and Technology Agency, Kawaguchi, Japan.
    2. Department of Dermatology, Mie University School of Medicine, Tsu, Japan.
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  • Kenji Nakanishi

    1. Department of Immunology & Medical Zoology, Hyogo College of Medicine, Nishinomiya, Japan.
    2. CREST. Japan Science and Technology Agency, Kawaguchi, Japan.
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* Kenji Nakanishi
Department of Immunology and Medical Zoology
Hyogo College of Medicine
1-1, Mukogawacho
Nishinomiya 663-8501, Japan
E-mail: nakaken@hyo-med.ac.jp

Abstract

Summary:  Interleukin-18 (IL-18) has been regarded as a proinflammatory cytokine because of its potent interferon-γ-inducing activity. However, mutant mice that release excess amounts of IL-18 spontaneously develop pruritic chronic dermatitis-like atopic dermatitis (AD), suggesting the importance of IL-18 for the development of AD. Intriguingly, depletion of il-18 but not stat6, an essential transcriptional factor for IL-4 signaling, rescues the mice from AD, indicating IL-18-dependent, T-helper 2 (Th2) cell-independent AD. This type of AD is classified as innate-type allergy in contrast to Th2 cell-dependent ordinary allergy. Consistent with the previous studies, mice transferred with antigen-specific Th1 cells exhibit no airway hyperresponsiveness and respiratory eosinophilic inflammation after challenge with antigen alone. However, they suffer from asthma upon challenge with antigen plus IL-18, with comparable levels of both the alterations as in those transferred with Th2 cells following challenge with antigen. The former type of asthma is categorized as Th1-associated allergy. Therefore, it is definitely necessary to evaluate whether individual allergic disorders involve either of these IL-18-mediated pathways or a Th2-mediated one.

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